Injury to weight-bearing ligaments such as the cruciate ligaments of the knee can occur, either as an isolated injury, or in combination with other ligament injuries of the knee. Damaged or torn cruciate ligaments can be repaired, reconstructed or treated nonoperatively depending upon the extent of the injury, the amount of functional or clinical laxity, the age of the patient, and the activity level desired. Simple repair of the injured ligament involves suturing, and because the cruciate ligaments are poorly vascularized, simple repair is generally insufficient. Reconstruction generally involves the utilization of synthetic ligament substitutes or autologous tissue within the knee joint similar to the cruciate ligament, such as in intraarticular reconstruction, or utilization of autologous tissue outside of the knee joint to strengthen the anterior or anterior lateral rotational stability, such as in extraarticular reconstruction.
Intraarticular reconstruction of anterior and posterior cruciate ligaments of the knee generally involves drilling holes through the tibia and femur followed by insertion of a ligament substitute such as patellar tendon, fascia, and the like through the central channel, and stapling of the ligament substitute to the outer surface of the bone adjacent the resected channel. The most common mode of failure is generally observed at the place where the ligament is subjected to stress; at the site where the ligament substitute enters or exits from the tibia or femur. Ordinarily the bone grows around and into the implanted ligament during the healing process leaving high stress concentrations at these exit sites. Moreover, the ingrowth of resected bone into the ligament implant throughout the length of the resected bone channel, which immobilizes the implant by restricting its naturally intended gliding motion and reducing its flexibility, may damage the implant due to sharp, jagged, irregular bone edges formed during the healing process.
Various attempts to improve the durability, compatibility, and mechanical functioning of naturally occurring and prosthetic tendons and ligaments have only been marginally successful. Such remedies include covering the ligament substitute with a vitreous carbon coating; plastic sheaths made of polyethylene, silicone rubber, and the like; silicone rubber-reinforced Dacron mesh sleeves; woven meshes of synthetic plastic fibers; stainless steel sleeves; metal wire meshes; and the like. Heretofore, implantable ligament substitutes in close proximity with resected bone have suffered the effects of irregular bone formation, high stress levels, and marginal durability.